Python tools to read flat CAFs and write to hdf5 files

[bear-is-asleep]

Written by Gray Putnam adopted by Bear Carlson for SBND. Used to write to hdf5 files that can be easily read into a pandas dataframe or numpy arrays (see README.md)

[bear-is-asleep]

I've cleaned up the code so that only the code necessary to read and write exist. I also included some test instructions in the README. I tested it after the most recent commit and the test cases still work.